Re: The things you see when ya go lookin'......

In article <43fcbf4b$1_4@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>, Serge Auckland
<serge.auckland@xxxxxxxxxxxxx> wrote:

[snip]

One oddity I've noticed. On the SILK attenuator pages, they say of
conventional resistor attenuators "That's why at high attenuation level
(low signal out, low listening level) the bandwidth of such volume
control is very poor and the bandwidth is not constant over any switch
position."

Can you give the URL for the page? I'm puzzled as I'd expect the maximum
output resistance of a conventional attenuator to occur at about the -6dB
setting, and fall as the output level is reduced below that. i.e. not have
a "poor bandwidth" at low settings, but at relatively high ones.

Is there some reason why the transformer referred to *doesn't* also have a
bandwidth that "is not constant" as the attenuation is altered? If nothing
else, I'd assume that the inductances, capacitances, and resistances, would
all tend to change, and affect the bandwidth...

This is only relevant if using very long high-capacitance cables. If
using cables of normal capacitance, and of normal domestic lengths, it
has no relevance as the bandwidth is already well in excess of the
audio bandwidth. Although I think a multi-tapped transformer as an
attenuator is a bit of overkill, it is a theoretically sound solution
as the output impedance will reduce as the attenuation increases.

Will the input impedance not also tend to change as the o/p tap is changed?

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html
.

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